Millions of mobile users have been warned they could be at risk of being scammed out of money as part of a major app fraud campaign.
Research from Sophos has revealed that "fleeceware" apps, which look to con users by exploiting free trial loopholes, are more widely-spread than originally thought.
The security firm believes that millions of iOS users have already installed such apps on their devices, meaning financial losses in the millions.
Through its SophosLabs research arm, the company detected more than 30 iOS fleeceware apps available to download on Apple's official App Store.
The malicious apps cover a wide range of themes, including image editors, horoscope/fortune telling/palm reader, QR code/barcode scanner, and face filters – and have been installed around 3.6 million times.
The apps promise a short time free trial, however they fail to alert users to when this period is set to end, quickly charging users a monthly fee instead. Many also require in-app purchases to use the apps properly, meaning users can end up paying far more than they expected.
Deleting the app often fails to cancel the payment thanks to a policy loophole that allows developers to create their own trial cancellation steps, with some forcing users to follow complicated and lengthy procedures to remove an app.
This is not the first cache of fleeceware apps uncovered by Sophos, which revealed a number of Android apps installed nearly 600 million times back in January.
“The main purpose of the iOS fleeceware apps we found seems to be severely overcharging users,” said Jagadeesh Chandraiah, senior security researcher at SophosLabs and the report author. “As was the case with the Android apps discovered in 2019, the app developers take advantage of monetization practices widely used by legitimate free apps, but take them one step further."
“Fleeceware apps are not officially malicious, but they are unethical, preying on consumer trust with devious techniques designed to make money. They appear to encourage unsuspecting users to install them through aggressive online advertising and what are likely to be fake five star reviews."
SophosLabs is recommending that Android and iOS users familiarise themselves with the necessary steps to better protect themselves against fleeceware, including knowing how to cancel an unwanted subscription (not just deleting it from a device) and taking a close look at an app before installing it.